Self-striking Water Clock

One of the important duties of the king of Joseon was to inform the people of the exact time. The intention was to regulate and control the rhythm of their everyday life to ensure social order by letting people know the time to rise, work, and rest. Therefore, the clock was a symbol of authority, order, and a means of rule. At that time, sundials and water clocks were used to measure time. The sundial could be used only during the day because its principle was to check the position of the sun by using its shadow, but the water clock could be operated over 24 hours because it worked on the principle of checking the increased (or decreased) amount of water. During King Sejong’s reign, the notification system of the water clock, which had been used since the Three Kingdoms Period, became automated, and it was called “Self-Striking Water Clock.”The automated clock was completed by Jang Yeong-sil by the order of King Sejong, and installed in front of the Borugak Pavilion, located to the south of Gyeonghoeru Pavilion in 1434, and served as the nation’s standard clock. This clock was used to inform injeong (time to open and close the gates of the city at around 10 pm) and paru (time to lift the curfew, around 4 am) and impose, ojeong (12 pm). The clock also became a standard clock for residents of Hanyang, the capital of Joseon, to help them keep the rhythm of their lives by informing the time for breakfast, lunch, and dinner. Hearing the sound of the drum and gong of each wooden puppet striking the water clock marked the hour for those in charge of striking the drum and gong at Gwanghwamun and Jonggak. Following these signals, the main gates of the palaces and city such as Sungnyemun, Heunginmun, and Donuimun were opened and closed. There were several names for the water clock. It was called Borugak-ru (Borugak Pavilion water clock) because it was installed in Borugak Pavilion, Geum-ru (Gold water clock) because it was located in the king’s palace, and Jagyeok-gung-ru (Self-striking royal water clock). The original water clock made during King Sejong’s reign was not preserved as it was, but was reconstructed in 1536, the 31st year of King Jungjong’s reign. Several water jars of the rebuilt water clock remain.